1. Field of the Invention
The present invention relates to a multi water-gas shift membrane reactor for producing high-concentration hydrogen and a method for producing hydrogen using the same. More specifically, the present invention relates to a multi water-gas shift membrane reactor wherein high-concentration carbon monoxide, obtained by dry-gasification performed by reacting dry bituminous coal with water and oxygen, reacts with water gas in the presence of catalysts in a single reactor, to produce hydrogen and carbon dioxide and separate highly pure hydrogen and carbon dioxide through a separation membrane arranged in a low region, and a method for producing hydrogen. That is, with respect to a synthetic gas containing hydrogen, carbon monoxide, carbon dioxide, hydrogen sulfide, hydrogen monoxide, etc., generated by partial oxidation and vapor gasification at a temperature of 1,300 to 1,500° C., 50-70% of carbon monoxide is converted into 99.9% or higher of hydrogen and 90% or higher of carbon dioxide in a multi water-gas shift membrane reactor containing vapor and low-temperature and high-temperature catalysts.
2. Description of the Related Art
Coal gasification to convert, coal, the most abundant fossil resource, into hydrogen, a next-generation energy resource, in order to cope with concerns about environmental pollution and depletion of resources such as petroleum or natural gas, attracts much attention.
Advantageously, coal gasification enables mass-production of hydrogen, widely considered to be the most environmentally friendly energy, and low-cost disposal of greenhouse gas, the fatal disadvantage of fossil fuels. Due to these advantages, a great deal of research is conducted to develop coal gasification technologies in many nations.
In the process of hydrogen production using coal gasification, more carbon monoxide than hydrogen is produced, depending on factors such as the type of coal used, gasifying agents, type of reactors and operation conditions. In particular, dry-gasification, wherein coal is directly injected without using a slurry-type coal, yields 50-70% by volume of carbon monoxide.
Accordingly, conversion of carbon monoxide into hydrogen is required for application to green-energy generation means such as hydrogen fuel cells, hydrogen engines and high-efficiency gas turbines. In addition, to realize low-cost separation of carbon dioxide, the advantage of the gasification process, high-concentration hydrogen streams composed of only hydrogen and carbon dioxide should be finally formed by converting carbon monoxide into hydrogen.
Generally, carbon monoxide is converted into hydrogen using a water gas shift reaction wherein carbon monoxide reacts with water to convert carbon monoxide into hydrogen and carbon dioxide, but the water gas shift reaction is unsuitable for use under the gasification condition that carbon monoxide is present in an amount of 50 to 70% by volume.
There are conventional water gas shift reaction-related technologies. For example, Korean Patent No. 612,956 discloses a catalyst for high-concentration conversion reactions and a method for preparing the same, and Korean Patent No. 462,286 discloses a water gas-converting catalyst wherein ceramic is incorporated into a metal and a method for preparing the same and Korean Patent No. 816,879 discloses a membrane reactor simultaneously performing reactions for modifying hydrocarbon water vapor and removing carbon monoxide and a method for preparing hydrogen using the same. Furthermore, Korean Patent Publication No. 2009-0015041 discloses a method for preparing carbon dioxide and hydrogen from a synthetic gas, as a process for modifying a natural gas comprising reaction of water gas.
Accordingly, there is a need for a single apparatus and a method for simultaneously reacting 50 to 70% by volume of carbon monoxide with water to produce hydrogen and carbon dioxide and separating the same, in order to improve preparation efficiency of hydrogen as a clean energy resource using dry coal gasification and to reduce process costs.